1. Field of the Invention
The present invention relates to a head cleaning apparatus for systems such as a video cassette tape recorder (hereinbelow, referred to as "VCR") and a digital audio cassette recorder (hereinbelow, referred to as "DAT") using magnetic recording/playback tapes, and more particularly to an automatic head cleaning apparatus for a magnetic recording/ playback system which has a cleaning roller variable in height so that an area of cleaning member being in contact with a head of the system is more widened, thereby allowing its useful life to be lengthened.
2. Description of the Prior Art
A magnetic recording/playback system, such as a video cassette tape recorder (VCR) and a digital audio cassette recorder (DAT) using magnetic recording/playback tapes, generally involves a problem that a head is likely to be contaminated because the head mounted on a head drum comes into contact with magnetic recording/playback tapes to read out information recorded on the tapes.
Since such a contamination of a head may cause a picture quality and a sound quality to be deteriorated seriously during playback operations, the head must be subjected to cleaning treatments periodically.
As such a cleaning treatment of a head, there has been proposed a method in which a head is cleaned by using a separate cleaning cassette. However, since the method necessitates a separate cleaning cassette additionally, the cleaning treatment is substantially cumbersome. Accordingly, there has recently been utilized an automatic head cleaning apparatus which is established in a player having the head to clean the head automatically.
With reference to FIGS. 1 and 2, there are illustrated a prior automatic head cleaning apparatus for a magnetic recording/playback system.
In FIG. 1, the known magnetic recording/playback system is constructed as will be described hereinafter. A head drum 20 is mounted on a base plate 10 of the magnetic recording/playback system. The head drum 20 comprises an upper rotating head drum 21 and a lower stationary drum 22. A head 23 is provided between the upper rotating head drum 21 and the lower stationary head drum 22. The head drum 20 is inclinedly mounted on the base plate 10 at a given angle with respect to the base plate. Two guide slots 40 are oppositely formed at the base plate 10 around and spaced away from the head drum 20, respectively. A slant post assembly 30 consisting of a base 31 and a slant post 32 and guide roller 33 attached to the base 31 is slidably mounted in each of the guide slots 40 (only one side of the head drum is shown in the drawing).
In the above-described magnetic recording/playback system, the known head cleaning apparatus is constructed as will be described hereinafter. An arm 50 is pivotably mounted at an end thereof on a pin 70 fixed to the base plate 10. As the slant post assembly 30 is moved rearwardly and forwardly, the arm 50 comes into contact with the slant post assembly 30 at a middle portion thereof, thereby allowing the arm 50 to be pivoted.
An operating lever 60 is pivotably mounted on the pin 70 at an end thereof and cooperatively connected with the arm 50. A cleaning roller 80 is rotatably mounted at the other free end of the operating lever 60. The cleaning roller 80 comes into contact with the head 23 of the drum 20 so as to clean the head 23 during a tape loading or unloading operation.
A torsion spring 71 is supported by the arm 50 at an end thereof and by the base plate 10 at the other end thereof so that the arm 50 is always caused to be biased in a clockwise direction.
Also, a spring 72 is connected with a spring hook 63 formed at the operating lever 60 at an end thereof and a spring hook 51 formed on the arm 50 at the other end thereof. Accordingly, as the arm 50 is moved in a counterclockwise direction, the operating ]ever 60 is pulled in the same direction by a tensile force of the spring 72 to be pivoted.
A stopper 73 is disposed between the operating lever 60 and the arm 50 and fixed to either of them. Therefore, the stopper 73 transmits a clockwise directional force of the arm 50 to the operating ]ever 60, thereby causing the operating lever 60 to be pivoted in a clockwise direction.
As illustrated in FIG. 2, the operating lever 60 is formed with a. Din supporting part 61 at the other end thereof. A cleaner supporting Din 90 is fixed to the pin supporting part 61. A cleaning roller 80 is rotatably mounted on the cleaner supporting Din 90. The cleaning roller 80 comprises a rotating roller 82 and a cleaning member 81 disposed on the circumferential surface of the rotating roller 82. Also, a washer 91 is inserted on and engaged with the cleaner supporting Din 90 in order to prevent the cleaning roller 80 from being separated from the cleaner supporting pin 90.
An operation of the above known head cleaning apparatus for a magnetic recording/playback system will be described as follows.
First, in case of a tape loading operation or unloading operation, as the slant post assembly 30 is rearwardly or forwardly moved along the guide slot 40 (herein the term "rearwardly" refers to the upward direction in FIG. 1), the base 31 of the slant post assembly 30 comes into contact with a middle portion of the arm 50 and pushes the arm 50 against the torsion spring 71 so that the arm is pivoted in a counterclockwise direction. Thus, as the arm 50 is pivoted in a counterclockwise direction, the operating lever 60 which is cooperatively connected with the arm 50 is also pivoted in a counterclockwise direction.
The arm 50 and the operating lever 60 are pulled to each other by the spring 72 and spaced apart from each other by the stopper 73 disposed therebetween, as mentioned above. Consequently, when the arm 50 is pivoted in a counterclockwise direction, the operating lever 60 is pulled to the arm 50 by means of the spring 72 and thus pivoted in a counterclockwise direction. On the other hand, when the arm 50 is pivoted in a clockwise direction, the operating lever 60 is pushed via the stopper 73 and thus pivoted in a clockwise direction.
Accordingly, when the arm 50 is pivoted in a counterclockwise direction, the operating lever 60 is also pivoted by the spring 72 in the same direction so that the cleaning roller 80 mounted on the free end of the operating lever 60 comes into contact with the head 23 of the head drum 20. At this time, since the upper head drum 21 of the head drum 23 is rotating continuously, the cleaning roller 80 is in contact with the rotating head 23 while being rotated, thereby carrying out cleaning action of the head 23.
Thereafter, when the slant post assembly 30 is moved to a tape loading completing position or a tape unloading position so that the slant post assembly 30 is disengaged from the arm 50, the arm 50 is pivoted in a clockwise direction by the torsion spring 71. Thus, the operating lever 60 is also pivoted in a clockwise direction by being cooperatively connected with the arm 50. Therefore, the cleaning roller 80 is moved to a position remote from the head 23 so that the apparatus completes the head cleaning action.
However, the above known head cleaning apparatus has disadvantages as will be described hereinafter. Since the cleaning member 81 of the cleaning roller 80 is rotated at a high speed in the condition of being pressed with the head 23 so as to clean the head 23, a contacting area of the cleaning member 81 of the cleaning roller 80 which is in contact with the head 23 is always fixed. Therefore, after the head cleaning apparatus is used for a long time, the contacting portion of the head 23 may be scratched and damaged by the cleaning member 81.
In addition, since the cleaning member 81 is locally and seriously contaminated along its narrow area corresponding to the head width after being used for a long time, the cleaning member 81 can not clean the head 23 any longer and on the contrary may contaminate the head 23. Furthermore, the cleaning roller 80 must be replaced with a new one because the cleaning member 81 is substantially shortened in its useful life. Hence, the head cleaning apparatus is not economical.